Multicenter, double-blind, placebo-controlled, parallel group comparison study to investigate the safety, tolerability, and efficacy of BAY 12-9566, a cartilage metalloproteinase inhibitor, as compared to placebo, in treatment of patients with mild to moderate osteoarthritis of the knee, over three months. A total of 204 patients will be enrolled, 17 will enroll at BMC, with symptomatic osteoarthritis of the knee.